Suzuki DR-Z400S 2001 Service Manual page 71

3-28 ENGINE
TOP NARROWING CUT
If the contact area is too high on the valve, or if it is too wide,
use the 30° cutter (for the intake side) and the 15° cutter (for
the exhaust side) to lower and narrow the contact area.
FINAL SEAT CUT
If the contact area is too low or too narrow, use the 60° cutter
to raise and widen the contact area. If the contact area is too
high or too wide, use the 15° cutter to lower and narrow it to
the correct width.
After the desired seat position and width is achieved, use the
60° cutter very lightly to clean up any burrs caused by the
previous cutting operations.
DO NOT use a lapping compound after the final cut is
made. The finished valve seat should have a velvety
smooth finish but not a highly polished or shiny one.
This will provide a soft surface for the final seating of
the valve which will occur during the first few seconds
of engine operation.
NOTE:
After servicing the valve seats, be sure to check the tappet clear-
ance after the cylinder head has been installed. (
Contact area too high and
too wide on face of valve
Contact area too low and
too narrow on face of valve
2-5 to 2-8)
w
30˚
W
15°
60˚